1. Field of the Invention
The invention relates to diaphragm pumps.
2. Discussion of Prior Art
Diaphragm pumps are commonly utilized for pumping a variety of fluids, such as chemicals, solutions and slurries. A diaphragm pump typically includes a pump head having a pumping chamber. A diaphragm forms a flexible wall enclosing the pumping chamber. The pump head includes a fluid inlet and a fluid outlet which communicate with the pumping chamber and with respective suction and discharge valves. The suction and discharge valves communicate with respective suction and discharge pipes in a piping system to permit fluid to enter the pumping chamber from the suction pipe and leave the pumping chamber into the discharge pipe. Typically, the suction and discharge valves are in the form of cartridges which are threaded into the pump housing and into a threaded connection with the respective suction or discharge pipe.
The diaphragm is driven by a connecting rod which is supported for reciprocal linear movement and which is driven by a rotatable eccentric. The eccentric and a worm wheel are mounted on a common rotatable shaft. A worm gear engages the worm wheel and thus drives the shaft and eccentric. The worm gear is connected to and rotates in common with an input shaft. The input shaft extends out of the gear box housing and at the outer end has mounted thereon a set of differently sized pulleys. Also mounted outside the gear box housing is a motor having an output shaft. A set of pulleys is mounted on the motor output shaft for receiving a drive belt. The drive belt engages one of the pulleys on the motor output shaft and one of the pulleys on the input shaft, such that the motor drives the input shaft and worm gear. The position of the drive belt can be changed between different pulley steps in order to selectively change the rotational speed of the input shaft relative to the motor.
U.S. Pat. No. 5,154,589 discloses a diaphragm pump including valve cartridges supported on the pump head with threaded collars. The pump head is provided with internal threads terminating adjacent to internal shoulders at each of the inlet and outlet valve ports. The inlet and outlet valves each include a flange which is secured to the shoulder by a collar threadably received in the respective port.